Craigiebuckler, Aberdeen, AB15 8QH, UK APPEARANCES CAN BE DECEIVING: Lessons Learned Re-implementing Axelrod’s “Evolutionary Approach to Norms” Luis R. Izquierdo 1 & José M. Galán 2 1 The Macaulay Institute, Aberdeen, UK 2 University of Burgos, Spain & INSISOC Group
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Craigiebuckler, Aberdeen, AB15 8QH, UK
APPEARANCES CAN BE DECEIVING:Lessons Learned Re-implementing Axelrod’s “Evolutionary Approach to Norms”
Luis R. Izquierdo1 & José M. Galán2
1 The Macaulay Institute, Aberdeen, UK2 University of Burgos, Spain & INSISOC Group
PRESENTATION OUTLINE
• Axelrod’s models• Method• Results and discussion• Conclusions
PRESENTATION OUTLINE
• Axelrod’s models• Method• Results and discussion• Conclusions
AXELROD’S MODELS: The Norms model
i defects
Boldness i > S
Temptation = 3Hurt = −1
i cooperates
each i
Enforcement = −2Punishment = −9
j punishes i
j does not punish i
Vengefulness j20-player PD
j sees i
j does not see i
S
each j≠i
AXELROD’S MODELS: The Norms model
• 20 agents; Random initial strategies• 1 round = 1 opp. to defect for everyone• 4 rounds = 1 generation
0 1 1 = 3 / 7
Avg +/— σReplicated
once
> Avg + σReplicated
twice
Payoffs
< Avg — σEliminated
• Evolutionary pressures
–MutationRate = 0.01– Selection mechanism
AXELROD’S MODELS: The Norms model
AverageVengefulness
AverageBoldness
1
10
5 runs
100 generations each
Norm collapse
Norm establishment
AXELROD’S MODELS: The MetaNorms model
j does not punish i
The Norms model
Vengefulness k
MEnforcement = −2MPunishment = −9
k meta-punishes j
k does not punish j
k sees j
k does not see j
S
each k ≠ i, j
i defects
Boldnessi > S
Temptation = 3Hurt = −1
i cooperates
j sees i
j does not see ieach i
S Enforcement = −2Punishment = −9
j punishes i
Vengefulness j
each j≠i
20-player PD
j does not punish i
AXELROD’S MODELS: The MetaNorms model
• 20 agents; Random initial strategies• 1 round = 1 opp. to defect for everyone• 4 rounds = 1 generation
0 1 1 = 3 / 7
Avg +/— σReplicated
once
> Avg + σReplicated
twice
Payoffs
< Avg — σEliminated
• Evolutionary pressures
–MutationRate = 0.01– Selection mechanism
AXELROD’S MODELS: The MetaNorms model
AverageVengefulness
AverageBoldness
1
10
5 runs
100 generations each
Norm establishment
Norm collapse
PRESENTATION OUTLINE
• Axelrod’s models• Method• Results and discussion• Conclusions